Mr Davis said that the talks will begin “in a positive and constructive tone, determined to build a strong and special partnership between ourselves and our European allies and friends”.
He added: “I’m in Brussels today, like Michel, to begin the next phase of our work to build a new, deep and special relationship with the European Union.”
But who is sitting at the negotiating table with Mr Davis and who will Theresa May have to face from the EU?
UK Brexit Team
David Davis – Brexit Secretary
Mr Davis, 68, has been the Prime Minister’s right hand man since his appointment as the Secretary of State for Exiting the European Union in 2016.
The seasoned politician and former SAS reservist is at the forefront of Britain’s exit strategy, insisting that Britain can and will walk away from a bad deal.
Despite this ultimatum, the Eurosceptic has expressed his wish to secure a “strong and special partnership” with the EU through the discussions.
In the run-up to the 2016 EU referendum, the Leave campaigner criticised the EU for failing to “modernise” and leading Europe towards “decline”.
Brexit Secretary David Davis is spearheading the Brexit negotiations
Senior civil servant Oliver Robbins, right, is joining Mr Davis
Oliver Robbins – Senior civil servant
Mr Robbins, 42, is one of Britain’s leading civil servants and will take over the reins from Mr Davis when the Brexit Secretary is in London.
As the former second permanent secretary at the Home Office, he can draw on his experience with immigration and border security when Britain hashes out an immigration deal.
Mr Robbins is said to be incredibly non-partisan and is known in the circles of Whitehall as Mrs May’s “sherpa” – the go-to-man for all important decisions.
He is the permanent secretary of the Department for Exiting the European Union and EU advisor to the Prime Minister.
Britain’s EU ambassador, Tim Barrow, handed the Article 50 letter to Donald Tusk earlier this year
Tim Barrow – British ambassador to the EU
Mr Barrow, 53, is the former ambassador to Russia who was sent to Brussels after his predecessor, Sir Ivan Rogers, resigned.
It’s the toughest negotiation in our lifetimes and I think he is up to it
He is recognised for his good grasp of European politics which could prove useful at the negotiating table.
Britain’s former ambassador to Lebanon, Tom Fletcher, told BBC Radio 4: “It’s the toughest negotiation in our lifetimes and I think he is up to it.”
EU’s chief negotiator Michel Barnier will lead the EU side of discussions
EU Brexit Team
Michel Barnier – The EU’s chief Brexit negotiator
Mr Barnier, 66, will lead the EU’s negotiating side, drawing on his experience as a former French minister and EU Commissioner.
The politician has been apprehensive of Britain’s withdrawal, threatening “severe consequences” if the UK leaves without securing a deal.
He hopes to conclude the Brexit talks with all divorce points laid out and agreed upon by October 2018.
German politician Sabine Weyand is the EU’s second in command after Mr Barnier
Sabine Weyand – The EU’s deputy chief negotiator
Ms Weyand is the EU’s second in command in the Brexit talks and will act as Mr Barnier’s deputy.
The German politician has a track record in crisis management and has been involved in developing the EU’s climate policies.
Prior to the negotiations, she was the deputy director general at the Commission’s trade department.
Her appointment also means that the EU’s two biggest founding states, France and Germany, will be at the heart of the negotiations.
Didier Seeuws is one of the Belgium’s top civil servants and the EU’s top negotiators
Didier Seeuws – Head of the European Council’s Brexit taskforce
The 51-year-old Belgian civil servant has been appointed by the European Council to aid the negotiations process.
His main claim to fame is negotiating a deal on a 30-year deadlock on the European patent system.
The Belgian newspaper La Libre Belgique has described him as a “fine intellectual machine” who knows “what the chances are for a short or long-term agreement”.